DESCRIPTION: Transplantation of neural stem or progenitor cells has been increasing proposed as a promising strategy to promote tissue regeneration and reconstruct the lesion cavity of TBI. However, poor control over the differentiation of human neural stem/progenitor cells (hNSCs) following transplantation, low survival and integration of the transplanted cells at the lesion site has severely limited the success of cell-based therapies. The objective of this study is to develop a nanoparticle-mediated transcription activation approach to direct the differentiation of hNSCs in vivo into functional neurons and oligodendrocytes. This new method will afford better control and higher efficiency of the survival, differentiation, maturation, and integration of the functional cells in vivo. We will demonstrate the advantages of this approach by transplanting transcriptionally activated hNSCs in a tailored hyaluronic acid hydrogel into a rat model of traumatic brain injury (TBI), and by examining cell survival, differentiation and integration of the transplanted cells, and tissue regeneration outcomes at the lesion site. Based on recent findings that over-expression of key transcriptional factors by viral transfection induces rapid and efficient production of functional neurons, and biodegradable nanoparticle transfection method capable of mediating efficient transgene expression in stem and progenitor cells, we plan to test the hypothesis that transient expression of stage-specific transcriptional factor neurogenin 2 (Ngn2) and oligodendrocyte transcription factor Olig2 in human induced pluripotent stem cell (hiPSC)-derived NSCs prior to transplantation will promote their in vivo differentiation towards functional neurons and oligodendrocytes, respectively. We will pursue the following specific aims in this exploratory grant: (1) to establish a highly effective nanoparticles for transfection of hiPSC-derived NSCs by plasmids encoding transcription factor Ngn2 and Olig2, respectively, and to investigate the effect of Ngn2 and Olig2 expression on neuronal and oligodendrocyte differentiation, respectively; (2) to demonstrate the directed differentiation of Ngn2-transfected and Olig2-transfected hNSCs derived from hiPSCs in vivo, and the advantage of hydrogel delivery in promoting the survival, differentiation, and maturation of the transfected cells and in enhancing tissue regeneration in a rat TBI model. This study will not only advance our understanding of transcription factor activation in regulating the survival, differentiation, and maturation of transplanted hiPSC-derived NSCs in vivo, but also offer new strategies for brain tissue regeneration in treating a wide range of traumatic injuries and neurodegenerative diseases. This new nanoparticle method together with the in situ forming hydrogels with defined compositions is highly desirable for clinical translation.